1. Field of the Invention
The present invention relates to a photosensitive resin, a photoresist composition having the photosensitive resin and a method of forming a photoresist pattern by using the photoresist composition. More particularly, the present invention relates to a photosensitive resin used for forming a pattern in a semiconductor device, a photoresist composition having the photosensitive resin and a method of forming a photoresist pattern by using the photoresist composition.
2. Description of the Related Art
Recently, as information media, such as computers, have become widely used, semiconductor devices included in the information media have become highly developed to have large capacities and high operational speeds. Thus, integrity, reliability and a response speed of the semiconductor device have been largely improved. In order to manufacture the semiconductor device, a photolithography process capable of forming a photoresist pattern having a relatively small line width is required.
The photolithography process for forming the photoresist pattern uses a photoresist composition. In case that light is incident onto a photoresist layer formed using the photoresist composition, a solubility of the photoresist composition in a developer may be changed. Particularly, the light may be provided onto a portion of the photoresist layer in an exposure process. The exposed portion of the photoresist layer is then removed in a development process using the developer. Thus, a desired photoresist pattern may be obtained.
The photoresist composition may include a resin. It is necessary that the resin have a high solubility in a solvent used in a coating process, a low absorbency of a light having a predetermined wavelength, a suitable adhesion and thermal stability.
Because the processes for manufacturing the semiconductor device are becoming complex, and the semiconductor device is becoming highly integrated, an improved photoresist composition capable of forming a fine photoresist pattern is being largely researched. In order to efficiently form the fine photoresist pattern, it is required that a difference in a solubility of the photoresist composition in the developer, between before and after the exposure process, is relatively large.
In order to increase the difference in the solubility, a conventional photoresist composition having a relatively low solubility in the developer before the exposure process has been used. However, in case that the conventional photoresist composition is used to form a conventional photoresist pattern, microbubble defects are unfortunately formed on the conventional photoresist pattern.
FIG. 1 is a cross-sectional view illustrating the microbubble defects generated on the conventional photoresist pattern formed using the conventional photoresist composition.
As illustrated in FIG. 1, particles 16 of an exposed portion of a photoresist layer formed using the conventional photoresist composition are attached to the conventional photoresist pattern 12 in the development process so that the microbubble defects 14 may be formed on the conventional photoresist formed on a substrate 10.
An example of a photoresist composition capable of suppressing the microbubble defects is disclosed in Japanese Patent Laid-Open Publication No. 2002-221795.
The photoresist composition of Japanese Patent Laid-Open Publication No. 2002-221795 includes a first resin and a second resin. The first resin and the second resin have a first degree of dispersion and a second degree of dispersion, respectively. A ratio of the first degree of dispersion to the second degree of dispersion is about 1.3 to about 9.9. In addition, the photoresist composition of Japanese Patent Laid-Open Publication No. 2002-221795 further includes a phenol compound including a hydroxide (OH) group to increase a solubility of the photoresist composition in a developer. In case that the photoresist composition of Japanese Patent Laid-open Publication No. 2002-221795 is used to form a photoresist pattern, a line edge roughness (LER) of the photoresist pattern is improved. However, the microbubble defects may still formed on the photoresist pattern.
Thus, an improved photoresist composition capable of forming a fine photoresist pattern on which the microbubble defects are hardly generated is widely researched.